The striker devices fitted to small or medium caliber guns generally comprise a striking pin which is guided to move in translation in a bolt that includes a front face against which the case of a cartridge to be fired is normally pressed.
The striking pin, or the striker assembly constituted by the striking pin per se and a striker mass, is associated with means for displacing it between a cocked position where the striking pin is retracted into the bolt and a firing position where the tip of the pin projects through the front face of the bolt to strike the cap in the cartridge.
For any given type of ammunition, the extent to which the tip of the pin projects is determined accurately by a minimum value for ensuring that the cap is always fired, and by a maximum value for ensuring that there is no danger of the cap being perforated by the striking pin (which would give rise to dangerous gas leakage).
The stroke of the striking pin is limited by abutment against the bolt mechanism such that the extent to which the tip of the pin projects from the front face of the bolt is constant.
However, it can happen that there is a relatively large longitudinal gap in the firing chamber between the front face of the bolt and the cartridge case, for example because of accumulated dimensional tolerances, because of a difference in thermal expansion, or because moisture has been taken up by a cartridge made of a non-metallic material. The clearance between the front face of the bolt and the cartridge case can then be greater than the extent to which the tip of the striking pin projects from said front face, in which case the cartridge will not be fired.
This drawback cannot be avoided by increasing the extent to which the tip of the striking pin projects from the front face since during recoil of the cartridge on being fired, the cartridge case comes into contact with the front face of the bolt and its cap could be perforated by the striking pin.
Swiss patent No. 666 119 describes a striker device for a firearm, said device comprising means for compensating clearance between the bolt and the cartridge case, which means are constituted by a moving part that moves in the bolt and that has the striking pin passing axially therethrough. Said moving part is entrained by the pin and presses against the cartridge case so as to define a constant projection distance for the tip of the striking pin when firing the cartridge cap.
In that known device, it can happen that the moving part remains in its firing position where it projects from the front face of the bolt, thereby impeding or preventing relative movement, e.g. transverse movement, between the bolt and the firing chamber, and also running the risk of depeding or preventing a new cartridge being moved into the firing chamber.
A particular object of the invention is to provide a striker device which is not subject to the above drawbacks, while still enabling clearance between the front face of the bolt and the cartridge case to be taken up.
Another object of the invention is to provide a device of this type in which the extent to which the firing pin projects in the firing position is determined very accurately so as to avoid perforating the cap of the cartridge.
Another object of the invention is to provide a device of this type suitable for use with an electrically-fired gun.